Dehydrator for liquid filled equipment



Aug. 4, 1942. JQG. FORD DEHYDRATOR FOR LIQUID FILLED EQUIPMENT Filed June 14, 1941 2 Sheets-Sheet l INVENTOR JG/72.95 G Fara.

BY M Z ATTORNEY Patented Aug. 4, 1942 D EHYDRATOR FOR- LIQUID FILLED EQUIPMENT James G. Ford, Wilkinsburg, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 14, 1941, Serial No. 398,071

7 Claims.

The invention relates to equipment for collecting and removing moisture from the gas space above the insulating liquid in liquid cooled and insulated apparatus, such as transformers, induction regulators, circuit breakers and the like.

In such apparatus, the gas space above the liquid is decreased and increased during the operation of the apparatus due to temperature changes therein which causes the liquid to expand and contract, thus changing the volume of the gas space. This action causes breathing between the gas space within the tank and the outside atmosphere resulting in moisture being taken into the tank with incoming atmospheric air, which is undesirable from the standpoint of maintaining the life of the insulating material. Moisture can also accumulate from oxidation of the insulating oil. The moisture may in time decrease the insulating strength of the liquid sufficient to cause failure of the apparatus.

When moisture is present in the gas space above the level of the liquid insulated equipment, a distillation process goes on more or less continuously. This process results in moisture condensation on the underside of the tank cover, which may drop back into the liquid insulating medium and eventually become localized in the insulation with resultant failure of the apparatus.

Various means have been used to prevent the intake of moisture into the tank, such as maintaining an atmosphere of dry nitrogen above the liquid level at a pressure above atmospheric pressure, so that breathing is always in one direction only, namely, from the tank to the atmosphere, and not in the reverse direction. Chemical means have also been provided to remove moisture from the atmospheric air taken into the tank while passing through the breather. In some cases, the space above the liquid is ventilated so that the incoming or ventilating air may absorb the moisture and carry it from the tank. This is undesirable in many situations partly because the incoming air itself contains a certain amount of moisture, and partly because the presence of the oxygen in the air in the gas space above the liquid oxidizes the liquid and shortens its useful life.

It is an object of the invention to provide means for removing moisture from the casing enclosing liquid immersed electrical apparatus without ventilating the gas space above the liquid and without the use of chemical absorbers.

Other objects and advantages of the invention will be apparent from the following description of certain preferred embodiments thereof, reference being made to the drawings, in which:

Figure 1 is a vertical sectional view of electrical apparatus embodying one form of the invention,

Fig. 2 is a sectional view of a portion of the apparatus casing illustrating another modification of the invention,

Fig, 3 is a top plan view of the condensing apparatus shown in Fig. 2, and

Figs, 4 and 5 are enlarged sectional views of the condenser structure shown in Fig. 2.

Referring to Fig. l of the drawings, a tank or casing I is illustrated containing electrical apparatus, such as a transformer 2, immersed in an insulating and cooling liquid, such as transformer oil, 3 above which there is provided a gas space 4 in a well-known manner. An opening is provided in the casing cover 6, which is closed by a member 5, which is heat insulated from the casing cover 6 by a heavy gasket 1, so that the heat from the electrical apparatus within the tank will not be readily conducted through the wall of the tank to the cover member 5. The cover member 5 may also be painted with aluminum paint or its equivalent to reflect the heat of the suns rays, and thus prevent the absorption of heat from the sun by the member 5 to the same extent as by the cover 6 and the main portion of the tank. The cover portion 5 is thus maintained at a lower temperature than the cover 6 and the rest of the tank structure.

A funnel-shaped condenser 8 is mounted on the underside of the cover 5 and may be welded to it. Since the condenser 8 and the cover 5 are heat insulated from the main cover 6 of the apparatus casing, and are cooler than the main cover, any moisture contained in the gas space 4 will tend to condense on the underside of the funnel-shaped member 8 rather than, or at a greater rate than, on the underside of the main cover portion 6. This moisture will collect and run down to the point of the condenser 8 where it will drop into a cup 9 provided for the purpose, from which a conduit I2 extendis outwardly through the side wall of the casing into a jar 13 where the moisture is collected, and from which it may be drained off through a valve I 4. A sight gauge I 5 may be provided for indicating the level of water within the jar l3, so that an observer may readily be aware of the necessity for draining the jar.

It will be appreciated that, due to the aluminum paint on the upper surface of the cover 5, when the apparatus is heated by the suns rays, the temperature rise will be much less on the cover 5 and condenser 8 than on the remaining portion of the apparatus, so that the condenser 8 will be at a lower temperature than the main cover 6 of the apparatus. It will also be appreciated that as the electrical apparatus contained within the tank is heated, heat will be conducted through the liquid insulating medium to the tank wall, and the main cover 6 will be heated to a higher temperature than will the smaller cover 5 and condenser 8 because of the heat insulating gasket 1 which prevents the conduction of heat from the main cover 6 to the cover 5.

Referring to Figs. 2, 3, 4 and 5 of the drawings, another form of the apparatus is illustrated which operates on the same principle as that illustrated in Fig, 1, but which in some respects is simpler in construction and more efiicient in operation. In the form of the invention shown in Figs. 2 to 5, an upwardly extended flange I6 is provided on the main apparatus cover 6, the upper edge of which engages a heat insulating gasket I! mounted between an inner flange I8 and an outer flange I9 extending downwardly from a frame member 22 of the condensing equipment. These two members may be welded or otherwise suitably attached to the frame member 22, which is provided with bolt holes 23, by means of which it may be readily attached by bolts to the cover 6 of the apparatus. In this form of the invention, the condenser element proper 24 consists of a cover member for the condenser equipment having inclined surfaces extending upwardly from the supporting frame member 22 as shown, and providing a trough 25 between the lower edge portion thereof and the upwardly extending rim of the flange member l8. An outlet tube 26 connects with the trough 25 to conduct any moisture collected therein to the jar 21 supported by the member 26 over the edge of the transformer cover. The form of the apparatus shown in Figs. 2 to 5 is simpler to attach, since it is unnecessary to provide for conducting the drain tube through the wall of the apparatus casing. Also, the condenser member 24, which extends upwardly an appreciable amount above the insulating gasket, is more readily cooled by passing currents of air, so that a greater temperature difference exists between the condenser member 24 and the main apparatus tank than is likely to be the case with the form of the invention illustrated in Fig. 1. The condenser member 24 may also be painted with aluminum paint to reflect the heat from the suns rays and prevent it from being conducted readily into the condenser top structure.

Modifications in the apparatus illustrated and described will be apparent to those skilled in the art, and I do not wish to be limited otherwise than by the scope of the appended claims.

I claim as my invention:

1. In combination, a tank containing electrical apparatus, an insulating fluid partly filling said tank, and means for collecting moisture from the space above the fluid comprising a moisture condensing member in contact with the gas within said space and with the outside atmosphere and separated from said tank by heat insulating material so as to be more subject to the cooling effect of the outside atmosphere than is the tank.

2. In combination, a metal tank containing heat producing electrical apparatus, an insulating fluid partly filling said tank, and means for collecting moisture from the space above the fluid comprising a moisture condensing member mounted on the cover of the tank and forming a part thereof in contact with the gas within said space and with the outside atmosphere and separated from said tank by heat insulating material so as to be more subject to the cooling effect of the outside atmosphere than is the tank and cover.

3. The combination with a tank containing therein partly filling said tank, of means for collecting moisture from the space above the fluid comprising a moisture condensing member in contact with the gas within said space and with the outside atmosphere and separated from said tank by heat insulating material so as to be more subject to the cooling effect of the outside atmosphere than is the tank, and means for receiving moisture condensing on said member and conducting it from the said space above the insulating fluid.

4. The combination with a tank containing electrical apparatus and an insulating fluid therein partly filling said tank, of means for collecting moisture from the space above the fluid comprising a moisture condensing member forming a part of the tank wall and thermally insulated from the tank wall, said member being in thermal contact with the space within the tank above the level of the liquid and with the outside atmosphere, means for collecting moisture condensing on said member, a chamber in communicaticn with said space and a conduit for conducting said moisture from said collecting means to said chamber.

5. The combination with a tank containing electrical apparatus and an insulating fluid therein partly filling said tank, of means for collecting moisture from the space above the fluid comprising a moisture condensing member forming a part of the tank wall and thermally insulated from the tank wall, said member having a raised portion extending well above the top of the tank and being in thermal contact with the space within the tank above the level of the liquid and with the outside atmosphere, means for collecting moisture condensing on said member, a chamber in communication with said space and a conduit for conducting said moisture from said collecting means to said chamber.

6. The combination with a tank containing electrical apparatus and an insulating fluid therein partly filling said tank, of means for collecting moisture from the space above the fluid comprising a moisture condensing member in contact with the gas within said space and with the outside atmosphere and separated from said tank by heat insulating material so as to be more subject to the cooling effect of the outside atmosphere than is the tank, the moisture condensing member having a surface on the side exposed to the outside atmosphere characterized in that it reflects heat more rapidly than the main tank wall and cover so that the suns rays will not impart heat thereto as rapidly as to the main tank wall.

'7. The combination with a metal tank containing heat producing electrical apparatus and an insulating fluid therein partly filling said tank, of means for collecting moisture from the space within the tank above the fluid comprising a moisture condensing member forming a part of the cover of the tank, said member being in contact with the gas within said space and with the outside atmosphere, and separated from said tank by heat insulating material so as to be more subject to changes in the temperature of the outside atmosphere than is the tank and the main portion of the cover, the moisture condensing member having a surface on the side exposed to the outside atmosphere that is more heat reflecting than the main tank wall and cover so that the suns rays will not impart heat thereto as rapidly as to the main tank wall.

JAMES G. FORD. 

